the l.a.x. shooter was gunned down,paulcianciatoldhim he acted alone. >> it isn't clear why he targeted tsa officers. what he left behind indicated he was willing to kill any of them that crossed his path. here's abc's david wright. >> moments before all of this, abc news learned paul ciancia's roommate dropped him off at l.a.x., thinking ciancia just had to catch a flight. instead what unfolded was a cold-blood attack. video surveillance shows ciancia walking up to the checkpoint at terminal three, pulling a smith & wesson out of his bag, and firing multiple shots at pointblank range at an officer. he looked back at the wounded officer, who appeared in video to move, and returned to shoot the officer again, killing him. the fbi says paul ciancia gunned down two more tsa officers as he shot his way through the terminal. >> he made a conscious decision to kill multiple tsa employees. >> reporter: the fbi said his bag contained five magazines full of ammo along with a handwritten letter signed by ciancia, addressing the tsa directly, saying, "he hoped to instill fare on your tra